An image formation apparatus such as a copying machine is provided with various kinds of process cartridges, for example, a photosensitive cartridge, a developer tank cartridge, a charging unit, and a cleaner unit, which are attached detachably to the image formation apparatus. Some of these cartridges deteriorate through usage. Consumable materials in some others among these cartridges are used up. Therefore, each of the cartridges needs to be replaced with another cartridge at an appropriate time. At this replacement, on one hand, the cartridge is replaced with a cartridge in a new state. However, on the other, the cartridge is replaced with a used cartridge (hereinafter, referred to as a cartridge in a used state), which has been used before but still usable.
In many of the image formation apparatuses, usage history of a process cartridge is recorded in order to (i) detect an appropriate time for replacing the process cartridge and then notify an operator of the appropriate time for the replacement and (ii) optimize process conditions according to the usage history of the process cartridge.
In case where the cartridge newly attached has not been used before (hereinafter, referred to as in an unused state) (in the new state), there is no problem in recording the usage history from a time when the cartridge is attached. However, in case where the cartridge newly attached is in the used state, the cartridge has been already used to a certain degree. Consequently, if the usage history of the cartridge in the used state is recorded from the time when the cartridge is attached in the same manner as the cartridge in the new state, the usage history may cause an error in (i) detecting the time for replacing the process cartridge or/and (ii) optimizing process conditions. Therefore, it is preferable that the image formation apparatus is arranged so as to be able to identify whether the process cartridge is in the unused state or in the used state when the process cartridge is attached to the image formation apparatus.
For example, Patent Documents 1 through 3 listed below disclose means for allowing the image formation apparatus to identify whether the cartridge attached is in the unused state or in the used state when the process cartridge is attached to the image formation apparatus.
(Patent Document 1)
Japanese Unexamined Patent Publication No. 99980/1990 (Tokukaihei 2-99980 (published on Apr. 11, 1990))
(Patent Document 2)
Japanese Unexamined Patent Publication No. 308277/1990 (Tokukaihei 2-308277 (published on Dec. 21, 1990))
(Patent Document 3)
Japanese Unexamined Patent Publication No. 271039/2003 (published on Sep. 25, 2003)
Patent Document 3 discloses an initial detection mechanism 200 as illustrated in FIGS. 6(a) and 6(b). This initial detection mechanism 200 is provided to a photosensitive cartridge attached to an image formation apparatus. The initial detection mechanism 200 includes (i) a shaft 230, (ii) a mobile body 210 fit on the shaft 230 so as to be capable of sliding in a direction of an arrow F (hereinafter, referred to as an F direction), and (iii) a cover member 220 on which an opening 220a is formed. The mobile body 210 has an axis body 210a. 
According to this initial detection mechanism 200, when the photosensitive cartridge is in the unused state, as illustrated in FIG. 6(a), the mobile body 210 is arranged at a position where the axis body 210a passes through the opening 220a from an inside of the cover member 220 and comes in contact with a sensor 250 of the image formation apparatus. Hereinafter, the position where the mobile body 210 is arranged as illustrated in FIG. 6(a) is referred to as a position a.
The mobile body 210 at the position a is pressed in a direction parting from the sensor 250 (the F direction) by a spring member 260 being compressed. However, the displacement of the mobile body 210 due to the pressure from the spring member 260 is restricted by a protrusion 210b formed on an outer periphery surface of the axis body 210a. The protrusion 210b restricts the displacement by abutting on an outer surface of the cover member 220 around the opening 220a. Thus, the mobile body 210 stays at the position a.
When the photosensitive cartridge is used, the shaft 230 rotates. Along with rotation of the shaft 230, the mobile body 210 and the axis body 210a also rotate (rotate around an axis that extends in the F direction). Moreover, due to this rotation, the protrusion 210b formed on the axis body 210a slides on the outer surface of the cover member 220 around the opening 220a of the cover member 220. Eventually, the protrusion 210b moves up to a position where the protrusion 210b faces a cut (not illustrated) made by cutting off a part of the outer surface of the cover member 220.
When the protrusion 210b faces the cut, the protrusion 210b does not abut to the outer surface of the cover member 220. This moves the mobile body 210 to the direction parting from the sensor 250 (in the F direction) by restoration force of the spring member 260. Moreover, as illustrated in FIG. 6(b), the mobile body 210 stops moving when a bottom surface inside the mobile body 210 abuts to an end of the shaft 230. As a result, the axis body 210a is arranged at a position away from the sensor 250. Hereinafter, the position where the mobile body 210 is arranged as illustrated in FIG. 6(b) is referred to as a position b.
The mobile body 210 arranged at the position b is supported by being pressed by the spring member 260 towards the end of the shaft 230. Accordingly, although the mobile body 210 supported at the position b may move a little in the direction of the position a (an opposite direction to the F direction) due to vibrations or the like, the mobile body 210 is eventually pushed back to the position b by the spring member 260. Consequently, the mobile body 210 is kept at the position b, and never goes back to the position a automatically.
According to the initial detection mechanism 200 as explained above, when the photosensitive cartridge is in the unused state, the mobile body 210 is arranged at the position a, and the axis body 210a of the mobile body 210 is in contact with the sensor 250 of the image formation apparatus. In case where the sensor 250 is in contact with the axis body 210a, the image formation apparatus identifies that the photosensitive cartridge is in the unused state.
Moreover, when the photosensitive cartridge is used, the mobile body 210 moves from the position a to the position b and the axis body 210a is away from the sensor 250. In case where the sensor 250 is not in contact with the axis body 210a, the image formation apparatus identifies that the photosensitive cartridge is in the used state.
In this way, in the initial detection mechanism 200, the image formation apparatus can identify whether the photosensitive cartridge is in the unused state or not.
In the initial detection mechanism 200, the mobile body 210 moves from the position a to the position b when the photosensitive cartridge comes to be in the used state from the unused state. Then, the mobile body 210 never returns to the position a automatically. However, it is possible by hand of an operator (a) to disassemble the initial detection mechanism 200 and (b) to reassemble the initial detection mechanism 200 so that the mobile body 210 is arranged at the position a again. The reason why this procedure is made possible is that the mobile body 210 is rearranged at the position a in the initial detection mechanism 200 of this photosensitive cartridge after the photosensitive cartridge returns to the new state (the unused state) by recycling of the photosensitive cartridge that has been used up and collected.
However, there may be a case where the photosensitive cartridge in the used state is to be reattached to the image formation apparatus, which photosensitive cartridge has been removed from the image formation apparatus and left in the used state (usable). In the arrangement mentioned above, an user or the like, who does not know that the photosensitive cartridge is in the used state, may (a) disassemble the initial detection mechanism 200 and (b) reassemble the initial detection mechanism 200 so that the mobile body 210 is arranged at the position a again. If such a case occurs, the image formation apparatus mistakenly identifies that the photosensitive cartridge, which is in the used state and reattached to the image formation apparatus, is in the unused state.